Arterial disease, primarily atherosclerosis is a major cause of death in many industrially advanced countries. This condition is caused by the build-up in a blood vessel of atherosclerotic plaques. The resultant stenosis occludes the vessel, thereby reducing the flow of blood to the brain and other vital organs, as well as placing undue strain on the wall of the vessel. Arterial sclerosis is inevitable with aging and is usually clinically silent until relatively far advanced, a characteristic which tends to frustrate attempts at early clinical diagnosis. Since means do exist for delaying and reducing the incidence of vascular occlusion, the early detection of arterial atheromatous plaque in critical vessels is of considerable value in that it would permit the application of such preventive interventions at a time when they could be most effective.
In the past, study of the atherosclerotic process in man has been difficult. The state of the arteries for diagnostic and investigative purposes has been assessed directly by vascular catheterization and arteriography. However, that technique is uncomfortable for the patient and it is invasive in that it entails risk of infection, bleeding and arrhythmia. There do exist various more or less noninvasive techniques for the diagnosis of arterial disease. These techniques include plethysmography, thermoraphy and ultrasound scanning, all of which are described briefly in the article Noninvasive Diagnosis of Arterial Disease, by Robert S. Lees and Gordon S. Myers, Annals of Internal Medicine, Vol. 27 (1982), pp. 475-509. While the aforesaid diagnostic tools do assist in the diagnosis of arterial disease, they are not able to recognize and quantify preclinical arterial disease reliably enough to determine the need for surgery or medical therapy. In other words, they do not detect the disease early enough to enable the physician to treat the disease by nonsurgical means such as by prescribing drugs or a proper diet. As a result, those prior procedures are used primarily to assist the physician to make a clinical decision as to whether or not a particular patient should undergo arteriography to define the need for surgery. Also, those prior more or less noninvasive diagnostic techniques are not accurate and reliable enough to be used to evaluate the efficiency of the various known long-term nonsurgical treatments for such vascular disease.